The O-specific polysaccharide of Proteus penneri strain 34 was
studied using 1H and 13C NMR spectroscopy, including
2D COSY, TOCSY, NOESY and H-detected HMQC experiments. The following structure
was established which is unique among the known structures of Proteus
O-antigens:

-4)bDGalpNAc(1-4)bDGalp(1-4)bDGlcp(1-3)bDGalpNAc(1-

Accordingly, no cross-reaction was observed between P. penneri
O34 antiserum and O-antigens of other Proteus strains. Therefore,
the strain studied shoud belong to a new Proteus serogroup O65.